Acute upper respiratory tract infections are the most common problem that most of us have encountered [1]. But in everyday life we often call them a cold, and from doctors we hear about SARS (acute respiratory viral infection). There are many reasons for SARS. The most common of them are influenza virus, rhinovirus, respiratory syncytial virus, adenovirus [2]. In recent years, metapneumovirus has become increasingly common, and today we’ll talk about it.
General information about the infection, characteristics of the pathogen
Human metapneumovirus is one of the causative agents of ARVI, which is the cause of respiratory tract infections in both children and adults [3]. Metapneumovirus was first described in 2001 in the Netherlands during an outbreak of SARS in children with severe cough, shortness of breath and high fever. After that, it was identified in different countries, it was found that they suffer from it regardless of the standard of living [4]. Also, further studies have shown that the metapneumovirus is not so new, because. It has caused ARVI for at least the last 50 years [3, 5]. Genetically, the metapneumovirus is closest to another, traditionally one of the top three causative agents of acute respiratory viral infections in children and adults – respiratory syncytial virus [6].
Metapneumovirus can cause ARVI throughout the year, but the peak of metapneumovirus infection has a clear seasonality and usually occurs in winter and early spring [4, 5]. However, according to official statistics in 2022, an increase in the frequency of detection of this virus has been noted since the second half of October [7]. And at the moment, metapneumovirus steadily occupies the 4th place in frequency among all causes of acute respiratory viral infections [7].
The virus is transmitted mainly by airborne droplets. Contact transmission is possible. Humans are considered the only source of infection because no animal species has yet been identified to isolate the virus. It has been established that this virus can persist on plastic surfaces for up to 48 hours, but is sensitive to all types of disinfection [6].
Risk groups
The first encounter with metapneumovirus occurs at the age of up to 5 years, and then ARVI associated with repeated infections due to weakened immunity or infection with another variant of the virus is possible throughout life [2, 3].
Most often, a more severe course of metapneumovirus infection is observed in children under the age of 1 year, the elderly and adults with a weakened immune system [5]. Also at risk for infection with metapneumovirus are people of any age with chronic diseases [8]. Individuals over 65 years of age, those with chronic heart and/or lung disease, and immunocompromised individuals have been found to be at higher risk of more severe metapneumovirus infection than younger individuals without comorbidities [3].
The effect of metapneumovirus on the human body (pathogenesis)
As a rule, patients with metapneumovirus infection are contagious from several days to several weeks after infection [2]. The incubation period averages 3-5 days.
A feature of metapneumovirus is the ability to affect the respiratory tract throughout – both upper and lower sections. In the body, it acts in the same way as most ARVI pathogens – first it enters the cell, then it begins to multiply in it and, leaving the cell, destroys it in order to penetrate into the next one to continue the reproduction cycle [9].
That is why, with metapneumovirus infection, as with other acute respiratory viral infections, the state of immunity and its ability to provide an adequate response to the virus with the help of special protective antiviral proteins – interferons and immune cells – lymphocytes and leukocytes are important. Since at the time of an acute viral illness and during the recovery period after an acute respiratory viral infection, there is a depletion of local and general immunity and a weakened body becomes especially susceptible to other viral and bacterial agents [10].
Symptoms of a metapneumovirus infection
In general, the symptoms of metapneumovirus infection are indistinguishable from the symptoms of other SARS [2, 3]. Sometimes it can be almost asymptomatic. But more often it manifests itself in various variants from mild infections of the upper respiratory tract with cough, runny nose, fever with temperatures above 38 ° C, which occur simultaneously, sometimes – sore throat and hoarseness, gastrointestinal manifestations (vomiting, loose stools), to severe lesions of the lower respiratory tract and lungs requiring hospital treatment [2, 11].
Features of the course of metapneumovirus infection in children
Russia is characterized by two seasonal rises in SARS caused by metapneumovirus in children: the first begins in November, gradually ends by the end of winter, the second – in May [2].
Since metapneumovirus can infect both the upper and lower respiratory tract, children with metapneumovirus infection most often have a runny nose, cough and fever [4]. Less commonly, eye damage can occur in the form of conjunctivitis, as well as damage to the digestive tract: vomiting, diarrhea. In some cases, there may be rashes, but they occur infrequently.
If a metapneumovirus attacks the lower respiratory tract, bronchitis (inflammation of the bronchi) can develop, in children – bronchiolitis (inflammation of the furthest and smallest parts of the lower respiratory tract), and even pneumonia (viral inflammation of the lungs) [2]. Due to inflammation, there is a pronounced difficulty in breathing with an increase in its frequency, cough and fever. The most severe metapneumovirus infection flows in the smallest. Metapneumovirus as a cause of ARVI is found in 10% of hospitalized young children [12-14].
Also, a feature of metapneumovirus infection in children is its quite frequent, almost in a quarter of cases, joint damage to the body with other ARVI pathogens [5].
Complications
Metapneumovirus, like other pathogens of acute respiratory viral infections, with untimely treatment, weakened immunity, can provoke the occurrence of bacterial complications. In children, this is most often acute otitis media, which occurs due to virus-associated swelling of the nasopharyngeal mucosa, which creates conditions for the reproduction of bacteria due to a violation of the outflow of mucus in a natural way [2]. Also, this virus is a provocateur of exacerbations of chronic lung diseases in more than 10% of cases [15].
Diagnosis of metapneumovirus
Children with metapneumovirus infections are examined and treated by a pediatrician, adults – by a general practitioner. Also, a general practitioner and an infectious disease specialist can help cope with a metapneumovirus infection. Diagnosis is carried out on the basis of examination of the patient, assessment of the manifestations of the disease. Laboratory methods can be used to determine the pathogen, for which it may be necessary to take a swab from the nose of the oral cavity. Typically, such studies are rare. If it is necessary to establish the degree of lung damage, a doctor may prescribe X-ray methods of examination, including computed tomography of the lungs [2, 14].In severe cases of metapneumovirus infection, treatment is carried out in a hospital (hospital), in other cases – at home in accordance with the doctor's recommendations [2, 14]. Of the general measures, it is usually recommended
- maximum isolation of the patient from other family members, especially from risk groups, limiting contacts with him;
- compliance with the sanitary and hygienic regime (wet cleaning indoors 2-3 times a day, airing, maintaining the air temperature within 20-22 ° C);
- easily digestible food with sufficient protein content (its best source in similar situation – lean boiled meat, fish). Dishes are best steamed, baked;
- providing the patient with sufficient drinking (clean water, fruit drinks from fresh or frozen berries, compotes, decoctions and infusions of herbs, rose hips).
In the medical treatment of metapneumovirus infection, the same approaches are used as in ARVI, since this virus is one of its causes [14]. The doctor may prescribe broad-spectrum antiviral drugs, drugs to ensure an adequate immune response to the infection, symptomatic agents, including antipyretics, antitussives, and so on. Obviously, the advantage should be given to combined drugs with a complex action against viruses and symptoms of acute respiratory viral infections, including cases of the agent caused by metapneumovirus [16]. For this purpose, for example, the domestic drug Ergoferon® can be used, which contains active substances for a powerful antiviral response, providing immunity support in the fight against the virus, and anti-inflammatory action to eliminate the symptoms of acute respiratory viral infections [17]. In experimental and clinical studies, the therapeutic efficacy of Ergoferon® in metapneumovirus infection has been established [17]. Ergoferon® is suitable for the whole family – it can be used in children from 6 months of age and adults [17].
Prevention: modern approaches and place of Anaferon®, Anaferon® for children in lozenges
A vaccine against metapneumovirus has not yet been developed. Therefore, preventive measures must necessarily include observance of generally accepted rules of personal hygiene: washing hands and/or using disinfectant solutions and wipes after returning from the street, self-control of touching dirty hands on the face, wearing medical masks, avoiding crowded places if possible during the peak of the influenza season and other SARS, including metapneumovirus.
It is important to strengthen the immune defense of the body: an environment that excludes increased psycho-emotional and physical stress, sleep at least 8 hours a day for adults, and for children – in accordance with age, stay in the fresh air , walking, hardening.
To prevent metapneumovirus infection, a doctor may prescribe courses of medications. Given the duration of the metapneumovirus peaks and the lack of the possibility of vaccination against it, preference is usually given to drugs with the possibility of a long course of administration. Among them, for example, attention is drawn to the time-tested and, at the same time, made on the basis of modern scientific achievements, Anaferon® and Anaferon® for children (lozenges) [18, 19].
The effectiveness of these drugs against metapneumovirus has been experimentally and clinically established [18, 19]. The drugs reduce the concentration of viruses in the body and support immune defense [18, 19]. For the prevention of acute respiratory viral infections, Anaferon® for children can be used in children aged from 1 month [19]. Anaferon® is suitable for adults over 18 years of age [18, 19]. It is worth noting the possibility of long-term prophylactic administration of Anaferon® and Anaferon® for children – courses from 1 to 3 months [18, 19].
Forecast
In general, with timely and complete treatment, the prognosis for recovery from metapneumovirus infection is favorable. As a rule, mild and moderate cases of metapneumovirus infection end in recovery within one to two weeks [20].
But don't underestimate this virus. Even in healthy adults presenting to a general practitioner with an acute cough and/or suspected lower respiratory tract infection, including cases of metapneumovirus infection, the severity of symptoms and their duration are known to be comparable to influenza [21]. Particular attention should be paid to those who are most vulnerable to this virus – their younger loved ones, the elderly and those with chronic diseases.
References
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